Structural characterization of two solvates of a luminescent copper(II) bis­(pyridine)-substituted benzimidazole complex

摘要

Copper(II) complexes of benzimidazole are known to exhibit biological activity that makes them of inter­est for chemotherapeutic and other pharmaceutical uses. The complex bis­(acetato-κO){5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)meth­yl]-1H-benzimidazole-κ² N ²,N ³}copper(II), has been prepared. The absorption spectrum has features attributed to intra­ligand and ligand-field transitions and the complex exhibits ligand-centered room-temperature luminescence in solution. The aceto­nitrile monosolvate, [Cu(C2H3O2)2(C20H18N4)]·C2H3N (>1), and the ethanol hemisolvate, [Cu(C2H3O2)2(C20H18N4)]·0.5C₂H₆O (>2), have been structurally characterized. Compound >2 has two copper(II) complexes in the asymmetric unit. In both >1 and >2, distorted square-planar N₂O₂ coordination geometries are observed and the Cu—N(Im) bond distance is slightly shorter than the Cu—N(py) bond distance. Inter­molecular π–π inter­actions are found in >1 and >2. A weak C—H⋯π inter­action is observed in >1.